In typical mining operations, water is used as part of the process to separate desired mineral from mined ore, resulting in an aqueous wastewater stream containing a combination of dispersed solids, fine particulates, and/or dissolved contaminants. This stream, known as the tailings stream, poses significant environmental, economic and operations issues for mines. The cheapest and most common way to handle tailings is to pump the fluid stream into an impounded area, called a tailings pond, where the suspended solids gradually settle out from the fluid over time while the water evaporates or is removed from the surface. This settling process can require years, even decades, for separating the solids from tailings fluids.
Tailings ponds have a number of adverse effects on the environment. They occupy a large surface area, disturbing the surrounding landscape by their very presence and occupying land that could be used more constructively in other ways. Tailings ponds also expose the environment to contaminants, including seepage of hazardous materials into groundwater and dispersion of hazardous materials into the air as dried particulate matter, i.e., dust. Metal ions are significant contaminants in tailings ponds. Economic considerations come into play here: because the tailings stream represents unusable waste to the mine operators, there is little incentive to adopt costly technologies for tailings management. There remains a need in the art, therefore, for a reliable, economical solution that can be readily implemented for solving the problems caused by tailings streams.